Correctly identifying the most important issue of our time, DiCaprio uses his clout and his carbon footprint to travel the world and ponder the incongruities.

Here is a heartfelt, decent, educational documentary about the most important issue of our time – climate change – presented by A-lister Leonardo DiCaprio, who proves his own commitment to the cause. His own interest began with an encounter with Al Gore in 2000 and has been a genuine passion with him since.

DiCaprio concedes that his own celebrity status is a double-edged sword. It draws attention to the topic, but allows the naysayers to say that he is a shallow, chuckle-headed movie star and this whole issue must therefore be a fad. There are brutal Fox TV news clips to this effect.

DiCaprio travels the globe (while cautiously conceding the carbon footprint issue – it is avowedly “offset” with a voluntary carbon tax payment) examining our fossil-fuel addiction, including emerging powerhouses such as India who now resent the idea of being denied the energy-consumption prosperity that the US has already enjoyed. The answer seems to be, of course, enforcing the 2015 Paris agreement, developing wind and solar power – although revisionist arguments for nuclear are not touched upon – and also a carbon tax.

Uncovering the impact of climate change … DiCaprio in Indonesia in Before the Flood. Photograph: RatPac Documentary Films

A shift in public opinion has to be achieved to change the political classes’ opinion: DiCaprio concludes with a ruminative walk-and-talk interview with President Obama himself, more interesting than his apparently wordless photo-op with the Pope. A serious, substantial piece of work.